Many of the 17 sustainable development goals (SDGs) are relevant to the food system. Agricultural and food cooperatives, as part of the Social and Solidarity Economy (SSE), are considering reinforcing and achieving SDGs. This paper focuses on their concrete sustainability behavior. Our methodology uses an original French database covering all the 186 agricultural cooperatives engaged in sustainable processes, including the 16 certified in ISO 26000. The study analyzes their motivations for Corporate Social Responsibility, how they engage their cooperatives and producers, and how they measure their social and environmental impacts. The results show that (1) proximity with consumers is a major motivation in innovating and adopting sustainability practices, thereby rendering (2) local interactions essential in order to reconcile economic, environmental and social dimensions. We suggest that Sustainable Supply Chains could provide an effective measurement of positive impacts, combining global as well as local levels. Our findings consider the appropriate mechanisms for the relational structuring of supply chains, since the quality of close interactions between stakeholders is essential for their sustainability. By applying their cooperative principles, cooperatives will be able to ensure another economic model, one that is more democratic, equal and sustainable for society and the planet.